窓部におけるダイナミックインシュレーション技術の適用: 第2報——冬季の温冷感評価と温度寄与率の検証

摘要

The urgent worldwide demand for the construction of low-energy buildings is well-known. A dynamic insulation system (DI system), which has been developed in cold regions such as those in the U.K. and northern Europe, has the potential to decrease energy consumption. In our study, we have applied the DI system to windows with poor thermal insulation performance. Through a chamber test and field test in a cold region, we have observed that the thermal insulation performance increased, depending on the airflow through the window. In comparison with the DI window and the conventional vent cap, the inlet air of the DI window was slightly higher than that of conventional ventilation. Conversely, the window surface temperature decreased owing to the outside cold air; thus, there was the possibility of worsening the indoor thermal environment. Namely, the DI window decreased the thermal insulation performance from the standpoint of the indoor environment, although it has increased the performance from the standpoint of the whole residential building. In this case, the influencing factors are radiant cooling from the window surface and a cold draft around the window. To verify the effect of the thermal comfort, the equivalent temperature defined by ISO-14505-2:2006 was considered, and a computational analysis was conducted. Initially, the equivalent temperatures were measured using a nude thermal manikin and a thermal manikin with cloth. The nude manikin is sensitive to convection effects such as a cold draft, and the thermal manikin with cloth was considered to be the thermal resistance (approximately 0.6 clo) between the manikin surface and the indoor environment. Next, the heat flux from the manikin was divided into the convection heat flux and the radiation heat flux by Computational Fluid Dynamics (CFD) with a surface temperature control model like the comfort control of a thermal manikin. Furthermore, the contribution ratio of the indoor climate of the glass surface and the frame of the DI window was analyzed relative to that of a conventional window. According to our measurements obtained by using a thermal manikin, regardless of whether the manikin was clothed or nude, the total equivalent temperature with the DI window installation decreased by a maximum of 5% of the difference of the indoor and outdoor temperatures. This result shows that the effect of the DI window on tiiermal comfort was minor. Our computational analysis indicated that the CRI around the DI window was approximately 0.9; hence, this means that there has also been a minor increase in the thermal comfort in the room. When comparing the DI window and the general vent cap, the latter exhibited a larger temperature distribution. Therefore, the DI window is not only increases the thermal insulation performance but also has a minor effect on the indoor thermal comfort.%建築物の省エネ化は世界的な課題であり、建築外皮の断熱化はこの課題解決に重要である。そこで著者らは見かけの断熱性能を向上させるダイナミックインシュレーション(DI: Dynamic Insulation)技術に着目をし、断熱性能の悪い開口部に適用し(DI窓)、その断熱性能向上の報告を行った。しかし流入する外気が若千の昇温をするとはいえ、対流による冷却や室内側表面温度の低下が報告されており、室内環境に影響が無いとは言えない。そこで、DI窓の冷放射•コールドドラフトの室内快適性への感度を検証した。実環境の等価温度と実測結果をもとに求めた室内温熱環境形成寄与率により、室内快適性に影響が小さいことを確認した。